Blends of silicone resins and epoxy resins have a tendency that the compatibility between silicone resins and epoxy resins becomes worse as the molecular weights of the resins increase. As the compatibility becomes worse, the amount of a low-viscosity compatibilizing agent must be increased. As a consequence, resin blends become lower in viscosity, which may have impacts on the operation to mold into cured parts and the cured properties. Depending on the amount of compatibilizing agent, effects like brittleness improvement which are essentially expected from the incorporation of high molecular weight polymers are lost in some cases. Thus it would be desirable to have means of enhancing the compatibility between silicone resins and epoxy resins without resorting to compatibilizing agents.
Reference should be made to JP-A 2005-158766 corresponding to US 2005/0129957.